Insulator



Qct. 22, 1929. R N 1,733,067

INSULATOR Original Filed May 10 I 1922 ATTORNEYS Patented Oct. 22, 1929 UNITED STATES PATENT OFFICE RICHARD H. MARVIN, OF EAST LIVERPOOL, OHIO, ASSIGNOR TO THE R. THOMAS & SONS COMPANY, OF EAST LIVERPOOL, OHIO, A CORPORATION OF OHIO INSULATOR Substitute for application Serial No. 559,844, filed May 10, 1922. This application filed August 2, 1927. Serial No. 210,189.

This application is a substitute for my abandoned application Ser. No. 559,844, filed May 10, 1922.

My invention relates to insulators, and particularly to power line insulators and the like, which are ordinarily exposed to more or less rapid temperature variations. The object of my invention is to provide temperature stabilizing means for association with such an insulator, and serving to minimize the rapidity of temperature change in certain exposed portions of the insulator, and thus to reduce the rupturing strains to which the insulator is subjected by rapid and unequal temperature change in different portions of the in sulator installation.

In the accompanying drawings Fig. 1 is a similar view of such an insulator provided with a temperature stabilizing 2 acket embodying my invention in one form;

Fig. 2 is a perspective View of a jacket of a modified type.

Insulators mounted on the towers or poles of high voltage systems are exposed to rapid temperature changes incident not only to vicissitudes of weather, but also in certain localities to marked and sudden temperature changes between day and night. The expansion and contraction of the insulator partsparticularly when the insulator is supported on a metallic pin, or is built up from a series of units connected by metallic unions-result in stresses on the porcelain which not infrequently result in its rupture, thus reducing or destroying its value as an insulator.

This danger is particularly present in insulators which have heads recessed to receive the metallic supporting pin or an associated member rigid with a pin or its equivalent.

In such constructions ruptures occur most frequently in the area at which the cap diaphragm of the head meets and joins the side walls of the latter with a bend of 90 or thereabouts. An example of such a rupture areais indicated at X in Fig. 1. On a drop of term perature radiation occurs first in the side walls 7 and cap 8 of the insulator head. The side walls 7 are supported by the head of the inner cone 9 of the insulator, which screws on 0 the metal pin 10, and are thus restrained from contraction as rapidly as the top diaphragm 8. Internal strains in the area X, at which the side walls 7 meet the cap 8, are consequently set up, which tend to rupture the insulator head at this point.

I have found that this difliculty may be in large part overcome if the insulator is provided with a suitable temperature stabilizing jacket 11, which in the form shown in Fig. 1 is of sheetmetal, provided with a heat insulating lining 12, and adapted to fit over the exposed head of the insulator. The acket may be supported in any suitable manner upon the insulator. For example, it may rest upon the skirt 13 and may be secured by a tie wire 14.- passed over the top of the acket and secured to the power cable 15. The latter is accommodated in a slot 16 formed in the side of the jacket 11. In addition to the insulating lining 12 of the latter, it will be noted that there is an air space 17 between the insulating lining and the cap of the insulator, this air space affording further means of heat insulation and temperature stabilization. A jacket of this type prevents rapid temperature change in the insulator head, and insures a more uniform variation thereof throughout the rigidly interconnected elements of the insulator-that is to say, the stud portion of the pin 10, cone 9, and elements 7 and 8 of the insulator head-and thus reduces the internal strains incident to rapid and unequal temperature change on these parts.

Various forms of jackets may be used. For example, in Fig. 2, 1 have indicated a jacket 18 of ceramicmaterial, such as terra cotta, or even of papier-mach, or other fairly good non-conductor of heat, which is capable of withstanding the weather without serious deterioration.

While I have indicated in the drawing merely an air space between the heat insulating jacket and the part which it surrounds, it is obvious that this space may be occupied in whole or'in part with such poor heat conductors as felt, magnesia, or any other material suitable for the purpose. In the following claims I use the term jacket in a sense broad enough to include such materials as portion of the jacket, although not necessarily mechanically associated with the outer jacket casing.

Various modified forms of construction will readily occur to those dealing with the problem, without departing from what I claim as my invention.

I claim 1. An insulator having a head portion comprising a side Wall, and an integral end diaphragm connected thereto by a substantially bend, said head portion being provided with a conductor receiving groove, in combination with a cap supported by the insulator and surrounding but out of contact with said bend to stabilize the temperature of the insulator head in the area of the bend, said cap having means through which the conductor may pass.

2. An insulator of the pin type having a head portion with an integral side wall and end diaphragm and a skirt in extension of said side Wall said head being provided with a conductor receiving groove, in combination with an insulating jacket supported on the skirt and enclosing the head of the insulator,

but out of contact therewith, said jacket comprising a poor conductor of heat and confinmg an air space around the insulator head.

In testlmony whereof I have signed my name to this specification.

RICHARD H. MARVIN. 

